The present invention relates to a fuse unit to be used mainly for, for example, an electric circuit for an automobile, and relates particularly to a fuse unit in which a metal part and a resin covering body are integrated by insert molding, and a method of manufacturing the fuse unit.
In the prior art, fuse units have been used to protect an electric circuit mounted in an automobile or the like and various electric components connected to the electric circuit. Specifically, when an unintended overcurrent flows in the electric circuit, a fusing portion fuses due to heat generated by overcurrent to protect the various electric components so as not to allow excess current to flow through the electric components.
There are various kinds of fuse units depending on the application, and, for example, the fuse unit described in Patent Literature 1 is used for connecting an on-board battery and electric wires supplying power to various electric components. In such an on-board fuse unit, there is a possibility that metal parts are damaged by vibration of a vehicle body. Thus, a resin is poured and insert-molded in a state where the metal part is disposed in a molding die, whereby the metal part and a resin covering body are integrated to avoid damage of the metal parts due to vibration.
The fuse unit may be provided with a connector portion used for attaching an external terminal from the outside. More specifically, as shown in a fuse unit 800 in FIGS. 6(a) to 6(c), the fuse unit 800 is formed by integrating a metal part 700 and a resin covering body 810 by insert molding, and the metal part 700 inside the resin covering body 810 is constituted of a connection-side terminal plate 710, an input terminal plate 720, and an external connection terminal 740. As shown in FIG. 6(c), a connector portion 900 is formed so as to surround a periphery of the external connection terminal 740. When an external terminal connector C2 provided with an external terminal C1 as a female terminal is attached so as to be fitted in the connector portion 900, the external connection terminal 740 is inserted into the external terminal C1, and both terminals are connected.
Here, a method of manufacturing the fuse unit 800 including the metal part 700 will be described. First, the metal part 700 is placed on a fixed side mold plate (not shown), and a movable side mold plate is mated with the fixed side mold plate from above of the metal part 700 to form a cavity. Then, when a resin is injected into the cavity, the fuse unit 800, as shown in FIGS. 6(a) to 6(c), in which the metal part 700 and the resin covering body 810 are integrated is completed. At that time, the connector portion 900 is molded integrally with the resin covering body 810.
However, as shown in FIG. 6(c), since the periphery of the external connection terminal 740 is surrounded by the connector part 900, it is difficult to connect inspection equipment or the like to the external connection terminal 740, and this causes difficulty in inspection of the fuse unit 800.